Mendelian Genetics: Key Terms (Segregation, Independent Assortment, and Beyond)

Vocabulary flashcards covering segregation, independent assortment, meiosis stages, gamete formation, types of crosses, basic probability concepts, and epistasis as discussed in the lecture notes.

Segregation (Mendel's Law 1)

Alleles for a gene separate during gamete formation, so each gamete receives one allele.

Independent Assortment (Mendel's Law 2)

Alleles of different genes segregate independently during gamete formation, allowing many possible combinations in gametes.

Meiosis

Cell division that produces haploid gametes from diploid cells; includes stages where segregation and independent assortment occur.

Prophase I

Stage of Meiosis I in which homologous chromosomes pair (synapsis) and crossing over may occur.

Metaphase I

Stage where paired homologous chromosomes align along the equator.

Anaphase I

Stage where homologous chromosomes separate to opposite poles; daughter cells become haploid.

Haploid

A cell with one set of chromosomes (n); gametes are haploid.

Diploid

A cell with two sets of chromosomes (2n); most body cells are diploid.

Homologous chromosomes

Chromosome pairs that carry the same genes in the same order, one from each parent.

Gamete

A haploid reproductive cell (sperm or egg) carrying one allele for each gene.

Fertilization

Union of two gametes to form a diploid zygote.

Independent events (Probability)

Two events whose outcomes do not influence each other.

P(X and Y) = P(X) × P(Y)

Rule for the probability of two independent events occurring together.

Combination series

Mendel's term for the probabilistic combinations of outcomes in his cross experiments.

F1 dihybrid (AaBb)

First filial generation heterozygous for two genes; can produce four gamete types: AB, Ab, aB, ab.

Parental cross

Cross between homozygous parents (e.g., AA × aa) producing F1 that is all Aa.

Hybrid cross

Cross between two heterozygotes (e.g., Aa × Aa); often yields ¾ A_ and ¼ aa phenotypes.

Test cross

Cross between a plant with unknown genotype (A_) and a homozygous recessive (aa) to reveal genotype.

Monohybrid cross

Cross involving a single gene (e.g., Aa × Aa) to study inheritance of one trait.

Dihybrid cross

Cross involving two genes (e.g., AaBb × AaBb) that assort independently and produce multiple phenotypic classes.

Branching diagram

A visual method to calculate phenotypic outcomes by multiplying branch probabilities in crosses.

Phenotype

The observable trait expressed by an organism.

Genotype

The genetic makeup of an organism; the alleles it carries.

Epistasis

One or more genes influence the expression of another gene (example: Labrador retriever coat color).